XXIIIrd International Eucarpia symposium, Section Ornamentals ...

SPECIFIC MAPPING OF DISEASE
RESISTANCE GENES IN TETRAPLOID CUT
ROSES
Control of fungal diseases is a major constraint of cut-rose cultivation in greenhouses
and in transportation around the world. Therefore, development of resistant cultivars is a
promising way to reduce the use of chemicals required for controlling the diseases.
Genetic analyses and breeding for resistance, however, are hampered by a high degree
of heterozygosity and the polyploid nature of cultivated roses.
Nucleotide-binding site (NBS) profiling of Van der Linden et al. (2004) was used as a
tool enabling a more directed way of studying the genetics of resistance to pathogens
responsible for diseases such as botrytis and powdery mildew.
NBS profiling is a multiplex screening technique, producing amplified resistance gene
analogue (RGA) fragments by using degenerated primers based on the conserved
motifs present in the NBS domain of resistance genes. Since NBS regions are
abundantly distributed and highly polymorphic within the plant genome, they are very
suitable as markers to identify resistance genes.
Twelve NBS degenerated primer/restriction enzyme combinations were used to
genotype the whole rose tetraploid K5 population and its parents (Yan, 2005). To
generate RGA profiles, the restriction enzymes: AluI, HaeIII, MseI, and RsaI were
combined with primers NBS1, NBS3, and NBS5a6. The profiles were dominantly scored
resulting in 135 polymorphic RGA markers which segregated in a 1:1 or 3:1 ratio.
The set of 135 markers, representing uni- and bi-parental simplex markers, were
mapped on the two available parental AFLP/SSR K5 maps with Joinmap 4.0
(unpublished). This resulted in two parental maps of 1150 cM and 1160 cM with 203
markers and 198 markers, respectively. The tetraploid maps will be used to dissect the
genetic variation for resistance to powdery mildew resistance.
Moreover, Rosaceae SSRs mentioned in the literature are currently tested on the K5
population to obtain allelic bridges between the tetraploid and diploid genetic maps in
rose and related species in order to align them. These bridges will improve cross-ploidy
comparisons in roses in order to strengthen cut rose breeding.
L17
C.F.S. Koning-
Boucoiran
O. Dolstra
C.G. van der Linden
J. van der Schoot
V.W. Gitonga
K. Verlinden
F.A. Krens
Wageningen UR Plant
Breeding. B.O. Box 16,
6700 AA Wageningen,
The Netherlands
Carole.boucoiran@wur.nl
Van der Linden C. G. et al. Efficient targeting of plant disease resistance loci using NBS
profiling. Theoretical and Applied Genetics, 109:384-393.
Yan Z. 2005. Towards efficient improvement of greenhouse grown roses: genetic
analysis of vigour and powdery mildew resistance. PhD Thesis, Wageningen-UR, The
Netherlands. 90pp..
Session Short presentations – Resistance breeding 43